ROCHESTER, Minn. — Jan. 21, 2014 —More people die and emergency hospital treatment takes longer for heart attack victims who arrive at the hospital during off-hours (nights and weekends), compared with patients who arrive during regular daily hours, according to a Mayo Clinic study published online in the British Medical Journal on Jan. 21.

Journalists: Sound bites with Dr. Sorita are available in the downloads.

Mayo Clinic researchers analyzed results of 48 studies published between 2001 and 2013 involving 1.8 million patients in the United States, Europe and Canada to assess the effect of off-hour hospital arrival for heart attack patients.

Patients who arrived at the hospital during off-hours are 5 percent more likely to die— both while in the hospital and 30 days after discharge — than patients who arrived at the hospital during regular daily hours. This resulted in an extra 4,000 deaths each year in the United States alone.

“The results show us that there are opportunities for us to improve care during the off-hours,” says Atsushi Sorita, M.D., first author and a senior fellow in preventive medicine at Mayo Clinic.

“Our research suggests that patients with acute myocardial infarction admitted during off-hours have worse outcomes after adjusting for clinical risk,” Dr. Ting says. “Understanding the factors that contribute to these vulnerabilities in our systems of care and staffing models during off-hours can potentially save thousands of lives.”

The authors offer caution to people who develop signs of a heart attack, such as chest pain or shortness of breath: the best action is to call 911 immediately, regardless of time of day or day of the week. The difference in risk of death between off-hours and regular hours does not warrant waiting in any circumstances, Dr. Sorita says.